A065983 Palindromes whose digit sum is 4.

4, 22, 121, 202, 1111, 2002, 10201, 11011, 20002, 101101, 110011, 200002, 1002001, 1010101, 1100011, 2000002, 10011001, 10100101, 11000011, 20000002, 100020001, 100101001, 101000101, 110000011, 200000002, 1000110001, 1001001001

Offset: 1

Author

Henry Bottomley, Dec 10 2001

Keywords

• base
• nonn

Comments

There are ceiling(k/2) terms with k digits and so floor(n^2/4) terms with fewer than k digits. Writing the terms as a vertical column and then blanking zeros produces a narrow triangle with upward chevrons.

Crossrefs

Cf. A062397 and A066138 for digit sums of 2 and 3.